C2-Elements compounds and mixtures

Question 1

Properties of metals

Answer 1

Shiny,solid at room temp,malleable,good conductors,form positive ions, metallic bonding

Question 2

Properties of non-metals

Answer 2

Dull, about half are solid half are gas (bromine is liquid), insulators, form negative ions, covalent bonding

Question 3

Ionic bonding

Answer 3

Metal + non metal

Strong electrostatic force of attraction between oppositely charged ions

Question 4

Properties of pure substances

Answer 4

• contain one element or compound

- Have a single melting point (usually higher then impure substances)

Question 5

Properties of impure substances

Answer 5

• melt over a range of temperatures

- impurities usually lower the melting point

Question 6

Diamond (carbon allotrope) properties

Answer 6

4 covalent bonds per carbon atom 
Giant covalent lattice
Hard
No delocalised electrons 
Does not conduct electricity

Question 7

Graphite (carbon allotropes) properties

Answer 7

3 covalent bonds per C atom 
Layered structure with weak forces between layers
Soft and slippery
Delocalised electrons 
Good conductor of electricity

Question 8

What are allotropes?

Answer 8

Different forms of an element in the same state but with different atomic arrangements

Question 9

Nanoparticles

Answer 9

Particles that are between 1nm and 100nm across (just a few hundred atoms)
They have a very large surface area to volume ratio

Question 10

What does filtration do?

Answer 10

• separates a solid from a liquid
• insoluble substances forms residue
• soluble substance goes through filter paper

Question 11

What does crystallisation do?

Answer 11

• produces a dry sample of soluble substance
• solution is heated
• solvent evaporates and is lost

Question 12

What does simple distillation do?

Answer 12

Separates a solvent from a solution

Evaporation->cooling-> condensation

Question 13

What does fractional distillation do?

Answer 13

• separates a solvent from a solution

- evaporation -> cooling -> condensing

Question 14

What does Chromatography do?

Answer 14

Separate liquid substance

Stationary phase (alumina or silica)
Mobile phase (water or gas)
Substances have different attraction to phases and so separate

Rt = distance travelled by substance/distance travelled by solvent

Question 15

Metallic bonding properties

Answer 15

-strong
-high melting points and boiling points
-conduct electricity when solid and liquid
Delocalised electrons

Question 16

Ionic compounds properties

Answer 16

• strong
• high melting boiling points
• conduct electricity when liquid or dissolved (ions flow freely)

Question 17

Properties of giant covalent structures

Answer 17

-strong
-high melting boiling points
-do not conduct electricity
Except graphite

Question 18

Properties of weak intermolecular bonds

Answer 18

• weak
• low melting and boiling points
• conduct electricity